(HealthDay News) – For patients with severe hemophilia B, a recombinant factor IX Fc fusion protein (rFIXFc) with prolonged half-life can safely reduce the frequency of injections, according to a study published online Dec. 4 in the New England Journal of Medicine.

Jerry S. Powell, MD, from the University of California at Davis, and colleagues examined the safety, efficacy, and pharmacokinetics of rFIXFc in 123 previously treated male patients (age ≥12 years) with severe hemophilia B. Participants were included in four treatment groups: Group 1 received weekly dose-adjusted prophylaxis; Group 2 received interval-adjusted prophylaxis; Group 3 received treatment as needed for bleeding episodes; and Group 4 received perioperative treatment.

The researchers found that rFIXFc exhibited a significantly prolonged terminal half-life. In Groups 1, 2, and 3 the median annualized bleeding rates were 3, 1.4, and 17.7, respectively. During the last three months of the study, 53.8% of Group 2 participants had dosing intervals of ≥14 days. Most bleeding episodes (90.4%) in Groups 1, 2, and 3 resolved after one injection. During all major surgeries, hemostasis was rated as excellent or good. No participants receiving rFIXFc had inhibitors; 73.9% of participants in Groups 1, 2, and 3 had at least one adverse event and 10.9% had serious adverse events.

“Prophylactic rFIXFc, administered every one to two weeks, resulted in low annualized bleeding rates in patients with hemophilia B,” the authors write.

Several authors are employed by Biogen Idec, which funded the study. One author disclosed working as a drug-development consultant in private practice.

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